chore: 著作権とライセンスについての情報を各ファイルに追加する (#11348)

* chore: Add the SPDX information to each file

Add copyright and licensing information as defined in version 3.0 of
the REUSE Specification.

* tweak format

---------

Co-authored-by: syuilo <Syuilotan@yahoo.co.jp>

packages/frontend/src/components/MkChartTooltip.vue

@@ -1,3 +1,8 @@
+<!--
+SPDX-FileCopyrightText: syuilo and other misskey contributors
+SPDX-License-Identifier: AGPL-3.0-only
+-->
+
 <template>
 <MkTooltip ref="tooltip" :showing="showing" :x="x" :y="y" :maxWidth="340" :direction="'top'" :innerMargin="16" @closed="emit('closed')">
 	<div v-if="title || series">